1. Field of the Invention
This invention relates to novel benzothiazepine derivatives and their methods of preparation.
2. Description of the Prior Art
It is generally known that angiotensin present in the blood acts on the smooth muscle of blood vessels to cause an intense contraction thereof and hence a marked rise in blood pressure. There are two forms of angiotensin: angiotensin I and angiotensin II. Renin, which is secreated by the kidneys, acts on angiotensinogen to form angiotensin I. By the action of the angiotensin converting enzyme present in blood plasma and tissues, angiotensin I is converted into angiotensin II. It is angiotensin II that has biological activities.
A rise in blood pressure could be checked by inhibiting the angiotensin converting enzyme from acting on angiotensin I. With attention focused on this idea, the development of compounds which are useful as drugs for the treatment of hypertension and other cardiovascular diseases has hitherto been carried on.
However, there have been obtained no compounds that are entirely satisfactory from the viewpoints of efficacy, side effects, toxicity and the like. Therefore, it would be still desirable to develop such compounds.
Moreover, pharmaceutical applications require that the desired compounds can be consistently produced in high yield and readily separated from by-products and the like.